Stackable container



June 27, 1967 D. J.A$ENBAUER 3,327,896

STACKABLE CONTAINER Filed June 4, 1965 5 Sheets-Sheet l I NVENTOR.

an 4.40M, Ari/164w? 1 BY J m 1967 D. J. ASENBAUER STACKABLE CONTA INER 5Sheets-Sheet 2 Filed June 4, 1965 31 MENTOR. am/44p u, Arm/@445? June27, 1967 D. J. ASENBAUER STACKABLE CONTAINER Filed June 4, 1965 5Sheets-Sheet 5 3; l1 i: i i i 1 i 1 INVENTOR 004/440 M. wan/1405a UnitedStates Patent 3,327,896 STACKABLE CONTAINER Donald J. Asenbauer,Whittier, Calif, assignor to Shell Oil Company, New York, N.Y., acorporation of Delaware Filed June 4, 1965, Ser. No. 461,313 14 Claims.c1. 220 a7 This invention relates generally to containers of the typewhich are adapted to be stacked one on top of the other during storageand shipment. The invention has more particular reference to an improvedstacking container of this type embodying novel vertical load-bearingreinforcing means and to a novel method of and apparatus for fabricatingthe container.

Most containers for handling and shipping articles of commerce aredesigned to be stacked one on top of the other during storage andshipment in order to permit optimum utilization of the available storageand shipping space. When filled containers are stacked in this way,there is imposed on each container a vertical load equal to the combinedweight of the overlying containers and their contents. The bottomcontainer in the stack, of course, is subjected to the maximum verticalload. Since any container may be placed at the bottom of such a stack,each container must be. designed to support the maximum load imposed onthe bottom container when the containers are stacked to their limitingheight.

Some containers, such as carboard containers for canned goods and thelike, are so designed that vertical stacking loads imposed on thecontainers are carried by the container contents. In this case, thecontainers themselves support little if any of the vertical load andthus may be constructed of relatively light weight material, sufficientin strength merely to confine the container contents during handling andstorage. Other containers, on the other hand, such as producecontainers, or produce trays as they are commonly referred to, must becapable of supporting the entire vertical load imposed thereon whenstacked. It is this latter type of stacking container with which thepresent invention is concerned.

Generally speaking, a stacking container of the type last referred toabove may 'be constructed in either of two ways. Thus, the main body ofthe container may be fabricated from a material which possessessufiicient strength to support the vertical loads imposed thereon whenthe container is stacked with other containers. Containers of this type,however, tend to be quite heavy, costly, and otherwise deficient.Alternatively, the main body of the container may be fabricated from arelatively lightweight or low strength material such as molded plastic,and auxiliary load-bearing reinforcing means may be incorporated in thecontainer to provide the latter with the requisite stacking strength.This invention is particularly con cerned with such reinforced stackingcontainers.

Accordingly, it is a general object of the invention to provide animproved reinforced stacking container as well as a novel method of andapparatus for fabricating the container.

A more specific object of the invention is to provide a reinforcedstacking container equipped with novel vertical load-bearing reinforcingmeans which are arranged to carry substantially the entire verticalstacking load imposed on the container when the latter is stacked withother like containers and to transmit this stacking load directly to theload-bearing reinforcing means of the adjacent lower container in thecontainer stack.

A related object of the invention is to provide a reinforced stackingcontainer wherein the load-bearing reinforcing means comprises verticalreinforcing rods, and wherein further the container is equipped withcomplementary upper and lower nesting formations which are 3,327,896Patented June 27, 1967 adapted for nesting interengagement with thelower and upper nesting formations, respectively, on adjacent containersin a container stack in such manner as to maintain the correspondingreinforcing rods or adjacent containers in coaxial alignment,particularly under load.

Yet another object of the invention is to provide a reinforced stackingcontainer comprising a main, one-piece molded plastic body, and whereinthe load-bearing reinforcing means of the container comprise metalreinforcing frames which are incapsulated within the plastic sidewallsof the body in such manner that the frames and their incapsulatingsidewalls mutually reinforce one another and said frames are shieldedagainst corrosion.

A related object of the invention is to provide a novel vacuum formingmethod and die for making a reinforced molded plastic containeraccording to the preceding object.

A further object of the invention is to provide a reinforced stackingcontainer which is constructed for frictional nesting engagement withother light containers, when empty, in such a way that the emptycontainers are frictional-1y restrained against separation under theaction of road-shock encountered during shipment.

Still a further object of the invention is to provide a reinforcedstacking container which is relatively simple in construction,economical to fabricate, light-weight and yet rugged and durable, andotherwise ideally suited to its intended purposes.

Other objects, advantages, and features of the invention will becomereadily evident as the description proceeds.

With these and other objects in view, the invention consists in theconstrution, arrangement and combination of the various parts of thepresent container and containerforming die, as well as the combinationof the various method steps involved in the fabrication of thecontainer,-

whereby the objects contemplated are attained, as hereinafter set forth,pointed out in the appended claims and illustrated in the accompanyingdrawings.

In these drawings:

FIGURE 1 is a perspective view of a stacking container according to theinvention;

FIGURE 2 is an enlarged section taken on line 22 of FIGURE 1;

FIGURE 3 is a section taken on line 33 of FIG- URE 2;

FIGURE 4 is a section taken on line 44 of FIG- URE 2;

FIGURE 5 is a section taken on line 5-5 of FIG- URE 4;

FIGURE 6 is an enlarged section taken on line 6-6 in FIGURE 2;

FIGURE 7 is a perspective view of a metal reinforcing frame embodied inthe container;

FIGURE 8 is a fragmentary vertical section taken through two stackingcontainers of the type illustrated in FIGURES 1 through 6;

FIGURE 9 is a view looking in the direction of the arrows on line 99 inFIGURE 8, with parts broken away for clarity;

FIGURE 10 is an enlarged section taken on the line 10-40 in FIGURE 8;

FIGUREv 11 is an enlarged section taken on line 11-11 in FIGURE 10;

FIGURE 12 is a perspective view of a vacuum forming die which is used inthe present vacuum forming method of fabricating the containerillustrated in FIGURES 1 through 11;

FIGURE 13 is an enlarged section taken on line lit-13 of FIGURE 12illustrating the die in perspective and showing a plastic sheet about tovacuumed formed in an initial position over the die cavity;

FIGURE 14 is an enlarged section taken on line 1414 in FIGURE 13 andillustrating the plastic sheet of FIG- URE 13 in a partially vacuumformed position within the die cavity;

FIGURE 15 is a section taken on line 1515 in FIG- URE 14;

FIGURE 16 is a section taken on line 16-16 in FIG- URE 14; and

FIGURE 17 is an enlarged fragmentary perspective view of the die cavity.

The stacking container of the invention which has been chosen forillustration in these drawings is intended primarily for use as aproduce tray for containing tomatoes or other similar agriculturalproducts. It Will become evident as the description proceeds, however,that the illustrated container may be used for other purposes and thatthe principal features of the invention may be employed in containers ofother configurations than that illustrated. As will appear later, theillustrated container is constructed of a plastic material, such asplastic and is fabricated by a novel vacuum forming process or method.

With this preliminary discussion in mind, the illustrated stackingcontainer 10 will be observed to comprise an integral body 12 includinga bottom, generally rectangular wall 14 bounded by a first pair ofgenerally parallel upstanding side walls 16 and a second pair ofgenerally parallel upstanding sidewalls 18. Bottom wall 14 is generallyflat and has a central upstanding rib formation 20 embossed therein fromits underside to reinforce the wall. Adjacent the side walls 18 thebottom wall has a pair of upstanding, linear rib formations 22 whichgenerally parallel the latter side walls. These latter rib formationshave a generally circular curvature in transverse cross section anddefine channels or grooves 24 in the under side of the bottom wall.

The container side walls 18 include panels 26 which are generallydisposed in planes normal to the bottom wall 14. Adjacent their loweredges the panels 26 slope inwardly at 26A and then continue in loweredge portions 26B which are generally normal to and merge with thebottom Wall 14. The junctures of the bottom Wall 14 and side wall panels26 define lower, arcuate edges 27 of relatively small radius. Adjacenttheir upper edges, the side wall panels 26 slope inwardly at 26C to joinhorizontal stacking shelves or ledges 28. These stacking ledges extendlengthwise along the upper edges of the side wall panels 26, from oneside wall 18 to the other, and extend laterally inward from the panelsin a common plane parallel to the bottom wall 14. Rising above thestacking ledges 28 is a rim or flange 30 which continues along the upperedges of the side walls 18 so as to completely encircle the upper, opentop of the container. Projecting inwardly from each side wall panel 26are a pair of vertical reinforcing ribs 32. These ribs extend betweenand are joined to the bottom wall 14 and the adjacent stacking ledge 28.The ribs are located about midway between the center and the ends of thestacking ledges. The outer surfaces of the panel 26 have verticalgrooves or channels 34 in line with these ribs. Opening centrallythrough the panels 26, just below the stacking ledges 28, are handholds36.

Side walls 18 of the container 10 comprise panels 38 which are generallydisposed in planes normal to the bottom wall 14. Adjacent opposite endsof each side wall panel 38 are a pair of generally rectangular, leg-likeformations 40. The outer surfaces 42 of these formations are located inthe same plane as the outer surface of the respective side wall panel38. The lower surfaces of the formations 40 are located in the sameplane as the under surface of the bottom wall 14. Each side wall panel38, in the region between the adjacent formations 40, slopes inwardly at38A and then continues in the lower, arcuate edge portion 38B whichmerges generally tangentially with the bottom wall 14. Adjacent itsupper edge, each side wall panel 38 slopes inwardly at 38C and thenextends laterally outward at 38D to join the lower edge of the containerrim 30. In the region between their ends, the side wall panels 38 arereduced in vertical height. Accordingly, the container rim 30, whichfollows the upper edges of the panel 38, drops within these regions to alevel below the remaining, co-planer portions of the rim, thereby todefine, at the upper edge of each side wall 18, a recess 44.

The adjacent ends of the container side walls 16 and 18 are joined bygenerally rounded corners 46 on the container body 12. These cornershave lower, inwardly sloping wall portions 46A which are generallyhorizontally aligned with the sloping wall portions 26A, 28A or theadjacent side walls 16, 18 and lower, rounded edge portions 4613 whichmerge generally tangentially with the lower container wall 14. Eachcorner 46 has a series of externally raised, vertically elongated ribformations 48 and intervening, vertically elongated valleys 50. As shownbest in FIGURE 4, the corner wall portions which define the ribformations 48 and valleys 50 have a generally semi-circular curvature inhorizontal cross-section. The curved wall portions of the adjacent ribformations and valleys at each corner 46 merge generally tangentially insuch a way as to define, in effect, a ninety-degree gear-like sector.These gear-like sectors form the subject matter of co-pendingapplication Ser. No. 337,954, filed Jan. 15, 1964, and entitled,Container Having Gear-Like Corners, and are provided to facilitateautomatic handling of the container, as explained in the latterapplication. Since the present invention is not concerned with thesegear-like sectors, no further description of the latter is deemednecessary.

As noted earlier, the illustrated container 10 is designed primarily foruse in the agricultural industry for handling and shipping agriculturalproducts, such as tomatoes, and is commonly referred to in such industryas a produce tray or a tomato tray. In accordance with the customarypractice in that industry, the container, or tray 10 is provided with anumber of ventilation openings 52.

Encapsulated within the container side walls 16 are metal, load-bearingreinforcing members 54. Referring to FIGURE 7, each reinforcing member54 will be seen to comprise a frame-like structure including a pair ofvertical, load-bearing reinforcing rods 56 and a horizontal,load-bearing reinforcing rod 58 which is welded or otherwise rigidlyjoined to the upper ends of the vertical rods 56. The vertical rods 56extend vertically through the reinforcing ribs 32 on the container body12, adjacent the vertical edges of these ribs. The horizontal rods 58extend horizontally through the stacking ledges 28', adjacent thehorizontal edges of these ledges. Referring to FIGURE 2, it will beobserved that the stacking ledges 28 comprise upper and lower walls 60and 62 which extend inwardly toward and finally around the horizontalreinforcing rods 58 of the respective reinforcing members 54. Thesewalls merge and are integrally joined about the rod, as shown. The upperledge walls 60 are integrally joined along their outer and end edges tothe lower edge of the container rim 30. The lower ledge walls 62 areintegrally joined along their outer edges to the upper edges of the sidewall panels 26, respectively, and along their end edges to the curvedwall portions of the adjacent container corners 46. In the regionsbetween the side wall panels 26 and the reinforcing members 54, thewalls 60, 62 of the stacking ledges 28 have contacting, confrontingsurfaces which extend through the outer sides of the container sidewalls 16 to join the outer surfaces of the side wall panels 26 and thecontainer rim 30, respectively. As will appear later, these confrontingsurfaces of the ledge walls may be bounded to one another.

Referring to FIGURE 4, it will be observed that the vertical reinforcingribs 32 on the container body 12 comprise side walls 64, 66 which extendinwardly from the side wall panels 26 toward and finally around thevertical reinforcing rods 56 of the reinforcing members 54. These ribwalls merge and are inwardly joined about the latter rods, as shown. Therib walls 64, 66 are integrally joined along their outer edges to theside wall panels 26, along their upper edges to the lower wall 62 of thestacking ledges 28, and along their lower edges to the curved walls ofraised, underlying rib formations 68 and the bottom wall 14 of thecontainer. These latter rib formations extend inwardly from the loweredge portions 26D of the side wall panels 26 to the rib formations 42 inthe bottom wall 14. In the regions between the side wall panels 26 andthe reinforcing members 54, the rib walls 64, 66 have contacting,confronting surfaces which extend outwardly through the outer sides ofthe container side walls 16 to join the outer surfaces of the side wallpanels 26. As may be best observed in FIGURE 4, the side wall panels 26curve inwardly, in the regions of the reinforcing ribs 32 to join theouter edges of the rib walls 64, 66 in such a way as to define thechannels or grooves 34 in the side walls 16.

The portions of the upper walls 68 of the stacking ledges 28, whichcurves up and over the horizontal reinforcing rods 58 on the reinforcingmembers 54 define, on the stacking ledges upper, upwardly presented,convex stacking surfaces 70 of generally circular curvature intransverse cross-section. The surfaces of channels or grooves 24 in theunder side of the bottom wall 14 of the container define lower,downwardly presented, concave stacking surface 72 of generally circularcurvature in transverse cross-section. The radii of curvature of theupper and lower stacking surfaces 70, 72 are approximately the same. Thelower ends of the vertical reinforcing rods 56 of the reinforcingmembers 54 terminate at the bottom wall rib formations 22 and mountplastic tips 74, for reasons to be explained presently. It issignificant to note, at this point, that the central axes of the severalreinforcing rods of each reinforcing member 54 and the axes of curvatureof the adjacent upper and lower stacking surfaces 70, 72 are locatedapproximately in a common verticel plane normal to the bottom wall 14 ofthe container.

From the preceding description, it is evident that each reinforcingmember 54 extends between and int-o vertical supporting relation withthe adjacent stacking shoulder 28 and the bottom wall 14 of thecontainer in line with the adjacent upper and lower stacking surfaces 70and 72. Accordingly, each reinforcing member may also be said to extendbetween and into vertical supporting relation with the adjacent upperand lower stacking surfaces.

Container is adapted to be stacked with other light containers, one ontop of the other, in the manner illu trated in FIGURES 8 through 11, toform a vertical container stack wherein the lower stacking surfaces 72of each container rest on the upper stacking surfaces 70 of the adjacentlower container. When the containers are stacked in this way, the bottomof each container in the regions of its reinforced end walls 16, nestswithin the portions of the rim 30 on the adjacent lower container whichextend along the upper edges of the side walls 16 and then along theupper edges of the side walls 18 to the recesses 40 of the lattercontainer. For convenience, the rim portions which extend along theupper edges of the container side walls 16 are designated by thereference numeral 30A and the rim portions which are located at oppositeends of the stacking shoulders 28 and extend from the rim portions 30Ato the container recesses 44 are designated by the reference numeral3013. In the stacked and nested positions of the containers, justreferred to, the lower edge portions 26B of the side walls 16 of eachcontainer fit between the rim portions 30A of the adjacent lowercontainer and the leg formations 40 of each container fit between therim portions 303 of the adjacent lower container. According to thepreferred practice of the invention, the space in between the lower edgeportions 26B of the container side walls 16 is related to the space inbetween the rim portions 30A, and the space in between the outersurfaces 42 of the container leg formations 40, at opposite sides of thecontainer is related to the space in between the rim portions 3013, insuch manner as to provide an interference fit between adjacent nestingcontainers in a container stack, thereby to frictionally restrain andsecure the adjacent containers against separation under the action ofroad-shock encountered by the stacked containers when the latter aretransported in an empty condition.

In addition to their other functions, discussed above, the rim portions30B, leg formations 40, and upper and lower stacking surfaces 70, 72provide locating means on the top and bottom of the container 10 whichare adapted for interengagement with the lower and upper locating means,respectively, on the adjacent containers in a container stack torelatively locate the adjacent containers in both edgewise directions ofthe bottom wall 14 in positions wherein the corresponding vertical,load-bearing reinforcing rods 56 of the adjacent containers arevertically or coaxially aligned. In this regard, it is evident that therim portions 30B and leg formations 40, by virtue of their interferencefit producing relationship mentioned above, provide upper and lowerlocating means, respectively, on the container 10 for verticallyaligning the corresponding vertical reinforcing rods 56 of adjacentstacked containers in one edgewise direction of the bottom wall 14, i.e.in the lengthwise direction of the stacking ledges 28. In other words,frictional nesting engagement of the lower leg formations, or lowerlocating means 40 on each container between the upper rim portions, orupper locat ing means 30B on the adjacent lower container in thecontainer stack vertically aligns the vertical reinforcing rods 56 inthe adjacent containers lengthwise of the stacking shoulders 28.Vertical alignment of the vertical rein-forcing rods 56 in adjacentstacked containers in the opposite edgewise direction of the bottom wall14, that is in a direction parallel to the container side walls 18 andtransverse to the stacking ledges 28, is accomplished by the engaging ormating stacking surfaces 70, 72 on the adjacent containers. Thus,referring to FIGURES 8 and 11, it will be observed that when a number ofthe containers are stacked, the convex upper stacking surfaces 011 eachcontainer enter the channels or grooves 24 defined by the lower stackingsurfaces 72 on the adjacent upper container to relatively locate theadjacent containers in a direction parallel to the container side walls18 and in a position wherein the corresponding vertical reinforcing rods56 in the adjacent containers are vertically or coaxially aligned. It isevident, of course, that the frictional nesting engagement of the loweredge portions 26B of the side walls 16 of each container between the rimportions 30A of the adjacent lower container also tends to relativelylocate the adjacent containers in the latter direction. However, theinterengaging stacking surfaces 70, 72 on the adjacent stackingcontainers provides a more effective and positive aligning or locatingaction for retaining the vertical reinforcing rods 56 of the adjacentcontainers in vertical alignment under load. This more positive aligningor locating action furnished by the stacking surfaces is desirable ornecessary, when the containers are loaded, since there is then atendency for the lower ends of the vertical reinforcing rods of onecontainer to shift to one side or the other of the horizontalreinforcing rods 58 of the adjacent lower container.

It is evident from the above discussion that when a number of thepresent containers are stacked one on top of the other, in loadedcondition, the vertical stacking load imposed on any given container bythe overlying containers is transmitted from the vertical reinforcingrods 56 of the adjacent upper container directly to the verticalreinforcing rods in the given container, and then through these latterrods directly to the vertical reinforcing rods in the adjacent lowercontainer. Accordingly, the reinforcing members 54 in the containerscarry the major portion of the stacking load imposed on each container.It is significant to note at this point that the side wall panels 26,stacking ledges 28, stacking ribs 32, and reinforcing members 54 tend tomutually reinforce and stabilize one another. Thus, for example, when anumber of the containers are stacked in loaded condition, the verticalreinforcing rods 56 of the containers are subjected to bending loads andto lateral forces which tend to shift the reinforcing members 54 ofadjacent containers out of vertical alignment. The stacking ledges 28and reinforcing ribs 32 tend to reinforce and stabilize the reinforcingmembers against bending and lateral deflection under the action of suchloads and forces. Conversely, the stacking ledges, reinforcing ribs, andreinforcing members tend to reinforce the side wall panels 26. Thesloping portions 26A, 26C, 38A, 38C, of the container side walls 16, 18also serve to reinforce these walls.

It will be immediately apparent to those skilled in the art that thebody 12 of the container described above may be constructed of variousmaterials and may be fabricated by various manufacturing techniques.According to the preferred practice of the invention, however, thecontainer is constructed of plastic and is fabricated by the uniquevacuum forming process or method which will now be described inconnection with FIGURES 13 through 17. In these latter figures, there isillustrated a vacuum-forming mold or die 76 having a die cavity 78. Theinner surface of this die cavity is contoured to form a sheet of heatedplastic into a container body having the shape described above andillustrated in the drawings when the sheet is forced outwardly againstthe side walls and bottom of the cavity. The various die cavityformations for this purpose will not be described except insofar as theyrelate to the present invention, which resides primarily in theincapsulated reinforcing members 54 and their associated containerstructure. With this in mind, the inner surfaces of the upstanding dieside walls are formed With an inwardly projecting rib formation 80 whichcooperates with the adjacent inner surfaces of the die side walls toform the sloping portions 26C, 38C of the container side walls 16, 18and the container rim 30. The inner surfaces of two opposite side walls82 of the die cavity have vertical grip formations 84 which form thechannels or grooves 34 in the container side wall 16. These ribformations extend from the bottom wall 86 of the die cavity to the upperedge of the adjacent portion 80A of the cavity rib 80. Rising from thebottom wall 86 of the cavity in spaced parallel relation to the cavitywalls 82, are rib formations 88. These latter rib formations form thegrooves or channels 24 in the bottom wall 14 of the container andthereby, the raised rib formations 22 which project above the uppersurface of the bottom wall. Extending from the lower end of eachvertical rib formation 84 in the die cavity 78 to the adjacent ribformation 88 is a rib formation 90 which rises above the bottom cavitywall 86 to a height somewhat greater than that of the rib formation 88.The rib formations 90 have inwardly pre-' sented end faces 92 disposedin vertical planes parallel to and off-set slightly from the centerlines of the respective bottom wall rib formations 88. Rib formations 90form the rib formations 68 on the bottom wall 14 of the container, atthe lower ends of the reinforcing ribs 32. The upper ends 84A of thevertical die cavity rib formations 84 slope inwardly, as shown. Theinwardly presented surfaces of these latter rib formations, and theupwardly presented surfaces of the die cavity rib formations 88, 90 arecurved in transverse cross-section, as shown.

Extending into the upper edges of the elevated portions 80B, whichextend along the die cavity side walls 92, adjacent the side walls 82,are notches 94. The two notches 94 located adjacent each side wall 82are disposed in a common vertical plane containing the longitudinalcenter line of the adjacent bottom wall rib formation 88. As shown inFIGURES 13 through 15, these notches are proportioned to receiveferrules 96 for positioning the reinforcing members of the container 10in the die cavity 78. Each ferrule 96 has a bore 98 extending part-waytherethrough and opening through one end thereof. These bores areproportioned to slidably receive the ends of the horizontal reinforcingrods 58 of the reinforcing members 54.

When positioning the reinforcing members 54 in the die cavity 78, theferrules 96 are fitted on the ends of the horizontal reinforcing rods 58of the reinforcing members, after which the outer ends of the ferrulesare dropped into the notches 94 in the die cavity 80. The verticalreinforcing rods 56 of the reinforcing members are so longitudinallydimensioned that when the reinforcing members are thus positioned in thecavity, the plastic tips 74 on the lower ends of the verticalreinforcing rods are located proximate to or axially seat against theupper rounded surfaces of the underlying rib formations 88. The tips 74seat laterally against the vertical end faces 92 of the adjacent bottomwall rib formations 90. These latter end faces are properly off-set fromthe center lines of the adjacent rib formations 88 to locate theadjacent reinforcing members in a vertical plane.

As noted earlier, the container 10 is formed by a vacuum-forming methodor process. To this end, the die 76 is provided with air passages (notshown) which terminate in a multiplicity of small ports distributed overthe upper edges of the die side walls 82, 92 and the inner surfaces ofthe die cavity 78. In actual practice, these air passages in the die areconnected to both a source of pressurized air and to a vacuum pump topermit selective introduction of air under pressure into and evacuationof the die cavity.

According to the present vacuum-forming method of fabricating thecontainer 10, a sheet 102 of plastic to be formed is clamped, along itsedges, in a frame 104 in accordance with conventional vacuum-formingpractice, and is heated to the proper vacuum-forming temperature. Theheated sheet is then placed over the die cavity 78 in contact with theupper edges of the die sidewalls, after which air under pressure isintroduced into the die cavity to expand the sheet upwardly away fromthe cavity, Thereafter, the sheet is forced downwardly into the cavityby a descending ram 106, again in accordance with conventional vacuumforming practices, and the die cavity is simultaneously evacuated. Theplastic sheet 102 is thereby forced, by atmospheric pressure, outwardlyagainst the inner surfaces of the die side walls 82, 92 and downwardlyagainst the bottom wall 86 of the cavity. Eventually, the portions ofthe sheet approaching the die side walls 82 encounter the suspendedreinforcing members 54. Thereafter, during continued outward movement ofthese sheet portions toward and into final contact with the die sidewalls 82, the sheet, in effect, wraps itself around the vertical andhorizontal reinforcing rods 56, 58 of the reinforcing members in such away as to incapsulate these members and form the stacking ledges 28 andthe reinforcing ribs 32. The outwardly moving plastic sheet portionswhich encapsulate the vertical reinforcing rods 56 encounter thevertical rib formations 84 on the die side walls 82. These ribformations, as already noted, form the external grooves or channels 34in the container side walls 16. The basic purpose of the rib formations84, however, is to provide curved junctures between the container sidewall panels 26 and the container reinforcing ribs 32, thereby to avoidthe formation of sharp, stress inducing corners at these junctures.Similarly, the upper, inturned ends 84A of the rib formations 84 aredesigned to avoid the formation of sharp, stressinducing edges at thejunctures of the container side-wall panel 26, stacking ledges 28,reinforcing ribs 32, and rim 30. It is evident that the above describedfunction of the vertical rib formations 84 on the die 76 requiresaccurate alignment with these rib formations, of the verticalreinforcing rods 56 of the reinforcing members 54. To this end, thebores 98 in the ferrules 96 for suspending the reinforcing members inthe die cavity are drilled to the proper depth to accurately align thevertical reinforcing .9 rods with the vertical, die cavity ribformations 84, when the ends of the ferrules seat against the adjacentdie side walls, as shown thus in FIGURE 15.

The outwardly expanding plastic sheet being vacuumformed, obviously,exerts substantial outward pressure against the reinforcing members 54,tending to move these members toward the adjacent die side walls 82.This outward pressure on the reinforcing members is resisted, in part,'by engagement of the ferrules 96 with the side-walls of the ferrulereceiving slots 94 and in part by engagement of the lower plastic tips74 on the reinforcing members against the end faces 92 of the lower ri'bformations 90 on the bottom wall of the die cavity.

If the plastic tips '74 were omitted from the reinforcing members 54,the lower ends of the vertical rods 56 of these members would directlycontact the die cavity rib formations 90. The plastic sheet beingvacuum-formed, therefore, would not be able to completely incapsulatethe lower ends of these rods, with the result that such ends would beexposed in the finished container. This exposure of the reinforcing rodsis undesirable for the reason that corrosion of the rods would occur.The plastic tips 74 are provided on the reinforcing members 54 toeliminate such corrosion. Thus, in the finished container, these tipsare partly exposed, as may be observed in the drawings, because of theircontact with the die cavity rib formations 90 during the vacuum-formingprocess. However, these tips completely enclose the lower ends of thevertical reinforcing rods 56 and thereby shield these rods againstcorrosion.

At the conclusion of the vacuum-forming process, the vacuum-formedcontainer is permitted to cool in the die cavity 78. During thiscooling, the container shrinks sufficiently to permit it to be liftedout of the die cavity. Thereafter, the excess plastic is removed fromthe container by routing or otherwise cutting the container along theupper edge of the container rim 30. The excess plastic is thus removedin such a way as to form the recesses 44 in the upper edges of thecontainer. When a number of the containers are stacked, in the mannerdescribed earlier, these recesses provide openings between adjacentcontainers which may be used for ventilation purposes as well as topermit dusting of the contents of the containers, when such contents areagricultural products, such as tomatoes.

Depending upon the particular material from which the present containeris constructed and/or the method which is used to fabricate thecontainer, the confronting walls 64, 66 of the container reinforcingribs 32 and the confronting walls 60, 62 of the container stackingledges 28 may fuse together to form integral wall structures, or theserib and ledge walls may remain in unfused contact. Fusion of theconfronting rib and ledge walls will occur, for example, when thecontainer is constructed of polyethylene or polypropylene and isfabricated by the vacuum forming process described above. On the otherhand, fusion of the walls may not occur if the container is constructedof various other plastics. According to the preferred practice of theinvention, the container is fabricated in such a way as to achievefusion of the confronting walls of the ribs 32 and stacking ledges 28,as by constructing the container of polyethylene or polypropylene andvacuum forming the container in the manner explained above.

Fusion of the confronting rib walls 64, 66 and stacking ledge walls 60,62 is desirable for the reason that such fusion prevents the entrance ofmoisture between these walls which would cause corrosion of thereinforcing members 54. In this connection, attention is again directedto the earlier discussion relating to the plastic tips on the verticalreinforcing rods 56 which prevent corrosion of the lower ends of theserods. After removal of the present container from the cavity 78 in thedie 76 following vacuum forming of the container, the ferrules 96 areremoved, thereby leaving openings in the con- 10 tainer side walls atthe ends of the horizontal reinforcing rods 58. These openings areclosed by plastic seals, as shown in FIGURE 6. It is apparent,therefore, that the reinforcing members 54 are totally incapsulatedwithin the container side walls 16 and are thereby totally shieldedagainst corrosion.

The container illustrated in the drawings is designed to supportsubstantial stacking loads on the order of 15-00 pounds. If such greatstacking strength is not required, the vertical reinforcing rods 56 maybe eliminated and in this case, the horizontal rods 58 are retainedprimarily to serve as forms about which the plastic material of the boxforms itself during the vacuum forming process, thereby to form thestacking ledges 28 and the upper convex stacking surfaces 70. Thehorizontal rods, of course, will continue to reinforce the stackingledges and the container as a whole to some degree. These rods, forexample, will transmit stacking loads in the stacking ledges to thecontainer side walls and will reinforce the container side walls againstbowing outward-1y.

While the invention has herein been shown and described in what ispresently conceived to be its most practical and preferred embodimentand practice, it is recognized that departures may be made therefromwithin the scope of the invention, which is not to be limited to thedetails disclosed herein, but is to be accorded the full scope of theclaims so as to embrace any and all equivalent devices.

Having described the invention, what is claimed as new in support ofLetters Patent is:

1. A stacking container comprising:

a generally rectangular bottom wall bounded by upstanding side walls,said container having upper, upwardly presented stacking surfaces alongthe upper edges of two opposite side walls and lower, downwardlypresented stacking surfaces at the under side of said bottom walldirectly below said upper stacking surfaces, respectively, metalreinforcing members including vertical load-bearing reinforcing rodsextending between and into vertical supporting relation with thevertically aligned upper and lower stacking surfaces, respectively, saidcontainer being adapted to be stacked with other like containers one ontop of the other to form a vertical container stack, wherein said lowerstacking surfaces on each container rest on said upper stacking surfacesof the adjacent lower container, and said container including upper andlower locating means at the top and bottom of said container,respectively, adapted for interengagement with the lower and upperlocating means on adjacent containers in said container stack forrelatively locating the adjacent containers in positions wherein thecorresponding vertical reinforcing rods in the adjacent containers areapproximately vertically aligned.

2. A stacking container according to claim 1 wherein:

each of said stacking surfaces extends crosswise of said containerapproximately parallel to said opposite side walls, each of saidreinforcing members comprises a pair of said vertical load bearingrein-forcing rods, and said reinforcing rods of each reinforcing memberbeing spaced along their respective upper and lower stacking surfaces.

3. A stacking container according to claim 1 wherein:

each of said reinforcing members comprises a pair of said load-bearingreinforcing rods, and a'horizontal reinforcing rod rigidly joined to oneend of the respective vertical reinforcing rods, said horizontalreinforcing rods being disposed in vertical supporting relation to theiradjacent stacking surfaces, and said vertical reinforcing rods beinggenerally symmetrically located at opposite sides of the center line ofsaid container extending between said opposite side walls.

4. A stacking container according to claim 1 wherein:

with the locating formations and rim, respectively, of the adjacentcontainers for relatively locating the adjacent containers in theopposite edgewise direction of said bottom wall.

said reinforcing members are incapsulated within said two oppositecontainer side walls, respectively.

5. A stacking container comprising:

a one-piece molded plastic body including a generally rectangular bottomwall bounded by upstanding side 5 9. A stacking container comprising:walls, said container body having upper, upwardly a one-piece moldedplastic body including a generally presented stacking surfa es along theu er ed rectangular bottom wall bounded by upstanding side of twoopposite side walls of said body and lower, Walls, tWo pp side walls ofSaid y including downwardly presented stacking surfaces at the un-Panels i p g n lly n p nes n mal o a derside of said bottom walldirectly below said upper bottom Wail, generally hoTiZOntal t g l gstacking surfaces, respectively, metal, load-bearing along the pp g s ofaid panels, respectively, and reinforcing members incapsulated withinsaid opextentiing iatereliiy beyond corresponding Sides of posite sidewalls and extending between and into Said P' aPProXirhateiY in CommonPlane vertical supporting relation with the adjacent upper eraiiyParaiiei to Said bottom Wail, Said Stacking and lower stacking surfaces,and said container being iedges defining pp hPWartiiY Presented Stackingadapted to be stacked with other like containers one Surfaces, saidbottom Waii having ioWer, downwardly on top of the other to form avertical container stack, Presented Stacking Surfaces the underside ofSaid wherein said lower stacking surfaces on each conbottom Waildirectly below Said PP Stacking tainer rest on said upper stackingsurfaces of the iaees, reSPeCtiVeiY, metai, dg reinforcing adjacentlower container and the corresponding reinmembers extending between andinto Vertical pforcing members of adjacent containers are approxi-Porting reitltion With Said Stacking ledges and Said mately verticallyaligned, whereby the vertical stacl bottom with in iine With theVertically aligned P- ing load imposed on each container in said stackis P and ioWer staeking Surfaces, respeetiveiy, and Said transmittedthrough the reinforcing members of the Container being adapted to bestacked With other like respective container directly to the reinforcingmem- Containers one on P of the other to form a Vertieili b ti l f h dj1 ,contaiheh container stack, wherein said lower stacking surfaces 6. Astacking container according to claim 5 wherein: on each Container reston Said pp Stacking ledges said load-bearing reinforcing memberscomprise vertioi the adjacent ioWer eontainer the Correspondcalload-bearing reinforcing rods extending between ing reinforeihg membersof the adjacent Containers and into vertical supporting relation withthe respecin Said stock are approximately Vertieaiiy aligned ri adjacgntupper d lower ki Surfaces, and 10. A stacking container according toclaim 9 wherein: said container comprises complementary upper and eachof Said reinforcing members Comprises a P of lower locating means at itstop and bottom adapted Vertieai, ioa'ti'hearihg reinforcing rodseXtendihg f interengagement i h the lower and upper locattween and intovertical supporting relation with the ing means, respectively, onadjacent containers in said respeetive adjeeent Stacking ledge and Saidbottom container stack to relatively locate the adjacent conwon in lineWith the respective adjacent upper mi i h edgewise directions of Saidbottom lower stacking surfaces and a horizontal, load-bearwall inpositions wherein said vertical reinforcing rods ing reinforcing rodrigitiiy joined to the Tipper ends of th dj Containers are approximatelyp of the respective vertical reinforcing rods and exlly h i 40 tendinglengthwise of the respective stacking ledge 7. A stacking containeraccording to claim 5 wherein: in Verticai Supporting relationtherewithsaid stacking surfaces extend crosswise of said container AStacking container according to eiairn 9 wherein: generany ll l to SaidOpposite Side Walls, each each of said opposite side walls includesreinforcing of said reinforcing members comprises a pair of vertiribsProjecting laterally from the respective Side Wail cal, load-bearingreinforcing rods extending between Panel in the e direction as theadjacent Stacking a d i t i l supporting relation with the resPecledgeand extending between the latter ledge and said ri dj t upper d lower kiSurfaces and a bottom wall, and each of said reinforcing membershorizontal load-bearing reinforcing rod rigidly joined Comprisesioad'bearing reinforcing rods ineapsuiated to one end of the respectivevertical reinforcing rods, Within the adjacent reinforcing ribs andextending said vertical r i f i d f h i f i between and into verticalsupporting relation with member being spaced lengthwise f h respectivethe adjacent stacking ledge and said bottom wall in stacking surfaces,and the horizontal reinforcing rod line With the respective PP andi'oWer Stacking of each reinforcing member extending lengthwise ofSurfaces and a ioed'bearing reinforcing rod P- the respective adjacentstacking surface in vertical Suieted Within and eXtendihg iengthWise ofthe j load-bearing relation therewith, and said container cent stackingledge in iine With the respective PP comprising upper and lower locatingmeans at the stacking Surface rigidly joined to the pp top and bottom ofthe container, respectively, adaptends of the respective first mentionedreinforcing ed for interengagement with the lower and upper 10-rodecating means, respectively, on adjacent containers i 12. A stackingcontainer according to claim 9 wherein: said container stack forrelatively locating the adeach of said opposite side walls comprises apair of jacent stacked containers in positions wherein the corverticalreinforcing ribs which project laterally from responding Vertical inf ring rods of the adj acent the respective side wall panel in the samedirection as containers are approximately Vertically aligned, theadjacent stacking ledge and extend between the 8. A stacking containeraccording to claim 5 wherein: latter ledge and said bOttOm Wall, saidribs bein an upstanding locating rim about the top of said conspacedlengthwise of the respective stacking ledges, tainer, locatingformations along the lower edges and each of said load-bearingreinforcing members of the remaining container side walls, respectively,comprises a pair of vertical, load-bearing reinforcing the verticallyaligned upper and lower stacking surrods incapsulated within theadjacent reinforcing faces having complementary shapes and beingadaptribs, respectively, and extending between and into ed forinterengagement with the stacking surfaces on vertical supportingrelation with the adjacent stackadjacent upper and lower containers insaid container ing ledge and said bottom wall in line with the restackto relatively locate the adjacent stacked conspective upper and lowerstacking surfaces and a tainers in one edgewise direction of said bottomwall, horizontal, load-bearing reinforcing rod incapsulated and said rimand locating formations on said conwithin and extending lengthwise ofthe adjacent tainer being adapted for nesting interengagement withstacking ledge in line with the respective upper stacking surface andrigidly joined to the upper ends of the respective vertical reinforcingrods.

13. A stacking container according to claim 9 wherein: each of saidopposite side walls comprises a pair of vertical reinforcing ribs whichproject laterally from the respective side wall panel in the samedirection as the adjacent stacking ledge and extend between the latterledge and said bottom wall, said ribs being spaced lengthwise of therespective stacking ledges, and each of said load-bearing reinforcingmembers comprises a pair of vertical, load-bearing reinforcing rodsincapsulated within the adjacent reinforcing ribs, respectively, andextending between and into vertical supporting relation with the adjacent stacking ledge and said bottom wall in line with the respectiveupper and lower stacking surfaces and a horizontal, load-bearingreinforcing rod incapsulated within and extending lengthwise of theadjacent stacking ledge in line with the respective upper stackingsurface and rigidly joined to the upper ends of of the respectivevertical reinforcing rods, each of said reinforcing ribs comprising apair of side walls which extend from the respective side wall paneltoward and finally around the respective vertical reinforcing rod, saidside walls of each reinforcing ri-b having contacting, confrontingsurfaces in the region between the respective side wall panel andvertical reinforcing rod and being integrally joined along therespective vertical reinforcing rod, each of said stacking ledgescomprising upper and lower walls which extend from the adjacent sidewall panel toward and finally around the respective horizontalreinforcing rod, and said upper and lower walls of each stacking ledgehaving contacting, confronting surfaces in the region between therespective side wall panel and horizontal reinforcing rod and beingintegrally joined along the latter rod.

14. A stacking container comprising: a one-piece molded plastic bodyhaving an open top and including a generally rectangular bottom wallbounded by upstanding side walls, two opposite side walls of said bodyincluding panels disposed generally in planes normal to said bottomwall, generally horizontal inwardly projecting stacking ledges along theupper edges of said panels, respectively, generally vertical inwardlyprojecting reinforcing ribs on said panels extending vertically betweensaid stacking ledges, respectively, and said bottom wall, said stackingledges defining upper, upwardly presented, convex stacking surfacesextending lengthwise of said stacking ledges, respectively, said bottomwall having lower, downwardly presented, concave stacking surfaces atthe underside of said bottom wall directly below said upper stackingsurfaces, respectively, an upstanding rim about the open top of saidbody rising above said upper stacking surfaces at least in the regionsof the ends of said upper stacking surfaces, metal load-bearingreinforcing members including vertical load-bearing reinforcing rodsincapsulated within said reinforcing ribs respectively, and extendingbetween and into vertical supporting relation with said stacking ledgesand said bottom wall in line with the vertically aligned upper and lowerstacking surfaces, and horizontal load-bearing reinforcing rods rigidlyjoined to the upper ends of the respective vertical reinforcing rods andincapsulated within said stacking ledges, respectively, in verticalsupporting relation with said upper stacking surfaces, said reinforcingribs having contacted side walls in the regions between their respectiveside wall panels and vertical reinforcing rods and being integrallyjoined around the latter rods and said stacking ledges having contactingupper and lower walls in the regions between their respective side wallpanels and horizontal reinforcing rods and being integrally joinedaround the latter rods, the contacting surfaces of said rib wallsjoining the outer surfaces of said side wall panels, respectively, andthe contacting surfaces of said ledge walls joining the outer surfacesof said side wall panels and rim, respectively, and said container beingadapted to stack with other like containers one upon the other to form avertical container stack, wherein the bottom of each container nestswithin said rim of the adjacent l-ower container and said lower stackingsurfaces on each container rest on said upper stacking surfaces of theadjacent lower container in such manner as to locate the correspondingvertical reinforcing rods of adjacent containers in approximate verticalalignment.

References Cited UNITED STATES PATENTS 2,676,729 4/ 1954 Neville 2207 32,840,256 6/1958 Cobb 220-4 3,147,882 8/ 1964 Waters 22097 FOREIGNPATENTS 1,353,129 1/ 1964 France.

THERON E. CONDON, Primary Examiner.

G. E. LOWRANCE, Assistant Examiner.

1. A STACKING CONTAINER COMPRISING: A GENERALLY RECTANGULAR BOTTOM WALLBOUNDED BY UPSTANDING SIDE WALLS, SAID CONTAINER HAVING UPPER, UPWARDLYPRESENTED STACKING SURFACES ALONG THE UPPER EDGES OF TWO OPPOSITE SIDEWALLS AND LOWER, DOWNWARDLY PRESENTED STACKING SURFACES AT THE UNDERSIDE OF SAID BOTTOM WALL DIRECTLY BELOW SAID UPPER STACKING SURFACES,RESPECTIVELY, METAL REINFORCING MEMBERS INCLUDING VERTICAL LOAD-BEARINGREINFORCING RODS EXTENDING BETWEEN AND INTO VERTICAL SUPPORTING RELATIONWITH THE VERTICALLY ALIGNED UPPER AND LOWER STACKING SURFACES,RESPECTIVELY, SAID CONTAINER BEING ADAPTED TO BE STACKED WITH OTHER LIKECONTAINERS ONE ON TOP OF THE OTHER TO FORM A VERTICAL CONTAINER STACK,WHEREIN SAID LOWER STACKING SURFACES ON EACH CONTAINER REST ON SAIDUPPER STACKING SURFACES OF THE ADJACENT LOWER CONTAINER, AND SAIDCONTAINER INCLUDING UPPER AND LOWER LOCATING MEANS AT THE TOP AND BOTTOMOF SAID CONTAINER, RESPECTIVELY, ADAPTED FOR INTERENGAGEMENT WITH THELOWER AND UPPER LOCATING MEANS ON ADJACENT CONTAINERS IN SAID CONTAINERSTACK FOR RELATIVELY LOCATING THE ADJACENT CONTAINERS IN POSITIONSWHEREIN THE CORRESPONDING VERTICAL REINFORCING RODS IN THE ADJACENTCONTAINERS ARE APPROXIMATELY VERTICALLY ALIGNED.